This invention relates to a tool of the type composed of a pair of mutually pivotable arm members such as cutting nippers, cutting pliers, round nose chain pliers with side cutters, scissors, pliers and pincers.
Conventionally, a tool of this type is assembled by inserting a cylindrical pin into through-holes provided at the fastening positions of a pair of two arm members and tightening a screw on the other end of the cylindrical pin which protrudes from the other side of the two arm members. As the arm members pivot about the pin-screw play is generated, unless the holes are precisely finished to a predetermined size. This play makes it difficult for the tool blades to be brought to the correct positions for their intended purpose. Japanese Utility Model Publication No. 30045/1983 discloses scissors in which any play of the nut is eliminated by augmenting the friction of coefficient between the nut and the washer through the association of a nut having a tapered peripheral surface and a washer having an end plate disposed at an angle of tape approximately the same as that of the above tapered peripheral surface.
In the tools discussed above, the nut and the washer are arranged in the tapered hole, which is only made in one member, so that the nut receives a screw. Even in this structure, a certain amount of play will be generated in the manner mentioned above unless the finish between the hole and the screw in the other arm member is precise.
Japanese Patent Publication No. 1082/1984 discloses a hand tool in which a tapered pin has a caulked pivoting portion which is associated with a tapered hole.
However, play is not eliminated in this tool either, because the tapered surfaces of the members are discontinuous. In addition, this hand tool is hard to repair because of its caulking structure.